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SKETCHING METHODS 



By W. C. SWEENEY 

Captain, Twenty-first Dnited States Infantry 



EDITED AT 

THE ARMY WAR COLLEGE 

OCTOBER, 1917 

And printed under the license of the 
grantee of the copyright 




Y^^^-^r^o- ^ 



WASHINGTON 
GOVERNMENT PRINTING OFFICB 

1917 



*^:^ 



AVAR DEPARTMENT, 

Document No. 679, 
Office of The Adjutant General. 



r; of ^. 

MAV 19 1920 



WAR DEPARTMENT, 

Washington, October 16, 1917. 
The following pamphlet, " Sketching Methods," Sweeney, is 
published for the information of all concerned. 
[461, A. G. O.] 
By okdeb of the Seceetaey of War : 

TASKER H. BLISS, 
General, Chief of Staff. 
Official : 

H. P. McCain, 

The Adjutant General. 

3 



CONTENTS. 

Page. 

Object of sketching 9 

Classification of sketches 13 

Outline for beginner 14 

Sketching tools 16 

To orient the board 16 

Conventional signs 21 

Title 25 

Scales 26 

What a sketch should show 31 

Horizontal detail , 32 

Traversing .• 32 

Intersection 32 

Resection 33 

Estimation : 33 

Vertical detail 34 

Contours 35 

Detail shown by contoiu-s 36 

Logical contoxiring 37 

Contoiu- framework 40 

Notes for field work 42 

Position sketch 44 

Adjustment to close 45 

Completing sketch 46 

Outpost sketch 46 

Place sketch 48 

Road sketch 48 

Reconnaissance sketches 51 

5 



INTRODUCTION. 

The writer's idea in publisliing " Sketching Methods " Is to 
simplify instruction in the subject and to clear away the 
mathematics and the mystei-y which seem to cling to it. The 
average student becomes confused because almost always he 
is required to s'tudy map making before he gets started on 
sketching and the result is a jumble of ideas until he learns to 
work without instruments. When he learns this he has learned 
to sketch. It is thought that a presentation, in as condensed 
form as possible, of the methods developed by expert sketchers 
at the Army Service Schools will be of great assistance not only 
to students but also to instructors. The writer believes that 
there is no necessity for teaching the use of the clinometer and 
scale of slopes in order to teach students how to contour. He 
believes that sketching can be taught more quickly and as thor- 
oughly by direct methods than by indirect ones. He has tested 
this belief and proved its soundness. In this time of emergency 
it is impossible to secure compasses, pacetallys, clinometers, 
tripods, and other expensive frills that have been a part of 
sketching for so long. Even if they could be procured there 
would not be time to teach their use, for intensive training 
means training under pressure and that means do away with 
frills and get down to practical and direct methods of instruc- 
tion. 

The student should be taught what scales are, how to make 
conventional signs and their meaning, how to locate points both 
horizontally and vertically, how to estimate differences of ele- 
vation of critical points, and how to contour by logical methods 
and finally what is to be shown on a sketch. He should then be 
given an area to sketch in a limited time for a definite tactical 
purpose. He should be given several such tasks to do, being 
always forced to work under pressure, and he will rapidly de- 
velop the ability to sketch. 

There is no reason why every officer and noncommissioned 
officer should not learn to sketch and to read sketches within a 
very short time. The instructor must thoroughly understand 

7 



8 INTRODUCTION. 

the subject. Common sense must be his guide. His explana- 
tions must be clear and simple, for the average man, especially 
one with a little service, is looking for something hard when 
you mention sketching to him. A pencil, paper, and home made 
ruler and board are sufficient tools for the experienced sketcher 
and should be enough for the beginner. 

W. C. Sweeney. 
. Peesidio, San Fbancisco, 

May 26, 1917. 



MILITARY SKETCHING. 

OBJECT OF SKETCHING. 

Military slietching is an art. Its general principles may be 
learned from textbooks, but the mechanical execution can no 
more be learned from them than can the art of painting. 
The degree of proficiency attainable depends upon the intelli- 
gence of the sketcher and the amount of time given to its 
practice. 

A map is a projection to scale of the topographic features of 
the ground. It is made with exact instruments, and its ac- 
curacy and completeness are the primary considerations in its 
making. 

A military sketch is a report of the topographic features of a 
section of country in which certain conventional signs are used 
as substitutes for words. Its accuracy and completeness are 
affected by the " time available," the " instruments at hand," 
and the " tactical conditions " xinder which the sketcher is 
working. The difference between a map and a sketch must 
always be in mind. 

A report by means of a sketch contains information which 
it is practically impossible to convey by written words. Every 
officer, below field rank, is liable to be called upon at any time 
to make a report on the country under such conditions that only 
a sketch will answer. All officers, especially those of field and 
higher rank, are constantly required to read maps and sketches 
and to make tactical decisions and dispositions based upon 
them. The ability to make a sketch guarantees the ability to 
read and understand both maps and sketches. A sketcher finds 
no difficulty in reading a map. Ridge and valley lines are at 
once apparent, and he reads the map easily, rapidly, and under- 
standingly. A sketch is more difficult to read than a map. 
One who is himself a sketcher has greater facility in reading a 
sketch, because he can grasp the sketcher's meaning more 
quickly than can one who has never sketched. 

In any well-regulated scheme of instruction for military offi- 
cers, military sketching occupies an important and distinct place. 
20171°— 17 2 9 



10 



SKETCHING METHODS. 



The necessity for having junior officers skilled in this art and 
the advantages accruing from the ability of field and higher 
ranking officers to read sketches quickly are recognized every- 




Scale: l"= I mi(e 



where. In the field, the report by means of a sketch is the 
rule, not the exception. 

An ordinary use of a sketch may be illustrated by the above 
assumed situation (fig. 1). 



SKETCHING METHODS. 11 

Our division is marcliing soutli, in liostile country, toward 
an enemy wlio was tliis morning reported to be about 20 miles 
soutli of us and moving north. Our cavalry screen is 4 miles 
south of Y. Our regiment forms the support of the advance 
guard. 

The colonel has a map of the country on a scale of 1 inch to 
the mile. This map was made several years ago. It shows 
only the flat detail, houses, towns, roads, railroads, stream 
lines, trees, etc. The undulations of the country are not shown. 

At a halt along the road the colonel calls to you, and, show- 
ing you his map, says : " I will arrive at Y at 4.30 p. m. to-day 
with the point of the advance guard. The division will camp 
to-night at Dover and the advance guard (less our regiment) 
about one-half mile south of Dover. Our regiment will form 
the outpost on a front from X (one-half mile west of Y) through 
Y to Z (1 mile east of Y). Take four mounted orderlies and 
reconnoiter from X to Z and far enough to the front for out- 
post purposes and report to me at Y on my arrival there. I 
want such a report as will enable me to determine how best to 
dispose the regiment for outpost duty without unnecessary 
delay." 

On the colonel's map you saw that Y is a crossroad formed by 
the road over which the division is marching and the straight 
X-Z road. 

You arrive at Y at 1 p m. You have three and one-half 
hours in which to make the reconnaissance. You must at once 
recognize that only by means of a sketch can you gather and 
convey the necessary information to the colonel. 

At 4.30 p. m. you hand your sketch to the colonel at Y. Read- 
ing it, he quickly gains an idea of the " lay of the land " and is 
able to dictate his order so that his troops may be marched 
directly to their several outpost positions. 

Sketches vary in the amount and value of the information 
that they convey in exactly the same manner as do written mes- 
sages and reports. The same faults are found in all. 

It must always be remembered that if there is plenty of time 
and conditions permit, the commander will send his engineers or 
others with accurate instruments to make a map of the desired 
area. As a consequence, sketches are made only when there is 
not time to make a map or when conditions do not permit it. 
The time required to make a sketch is always a most important 
factor. It will usually be found that the sketch is wanted for 



12 SKETCHING METHODS. 

use just as soon as it can be gotten, and often that it is wanted 
in such a short time that only an outline of the desired area can 
be made. It is in such a case that the judgment, experience, 
and tactical training of the sketcher play such an important 
part. If the sketch must be slighted in some parts he must be 
able to determine what parts to slight and where accuracy and 
detail are necessary, and he can not determine this unless, 
knowing the object for which the sketch is made, he realizes 
what the commander needs to know about the ground. 

From the foregoing considerations certain conclusions have 
been deduced for the guidance of the sketcher. These may be 
summarized as follows : 

(1) The assigned area or distance should be covered in the 
time allotted. 

(2) Clearness is very important. No matter how much valu- 
able information may be gathered, it will be of little use unless 
it be clearly shown. 

(3) The sketch should contain all data of military value to 
the purposes for which it is needed. It may be a model in its 
technique and yet have left out some feature of such military 
value as to make it of little or no use. 

(4) A sketch may be inaccurate in many of its measurements 
and still be so clear in showing what is meant and have such 
military value that the inaccuracies make no difference. Accu- 
racy, therefore, though always to be sought, must be subordi- 
nate in a relative degree to finishing the task in the time allotted, 
to clearness of expression, and to military value. 

The rehitive importance of the foregoing principles may be 
determined in each case by a careful summing up of the require- 
ments of the situation which calls for the sketch. 

In the assumed situation cited, you should be able to deter- 
mine at once just what the colonel will want to know about the 
area before issuing his outpost order. You should, therefore, 
know what features and distances to estimate and what to meas- 
ure, where to go fast in your work and where to go slow. 

Summing up the situation, you would realize — 

(1) That the colonel will need to have a sketch of the whole 
area before him. 

(2) That the information contained in the sketch must be so 
clear that there can be no mistake about what is meant. 

(3) That all features which have value in outpost duty should 
be especially noted ; for instance, a hill about 300 yards south 



SKETCHING METHODS. 13 

of Y, commanding the road from the enemy^ can be held by com- 
paratively few men. The strength of this position must be indi- 
cated on the sketch, as it has a direct bearing on the number 
of men assigned to the various sectors. 

(4) That the sketch must be as accurate as possible, consistent 
with (1), (2), and (3). 

There may arise cases where the judgment of the experienced 
sketcher will cause him to change the relative value of the fore- 
going principles. This is to be expected, because each sketch is 
a problem in which the sketcher must use his best judgment in 
determining how to gain and to convey the desired information. 

The beginner, however, must learn to sketch before he can pay 
much attention to these considerations. Clearness, accuracy, and 
speed in the order named should be his guide until he has 
attained a fair ability in making a sketch. 

The habits formed in learning to sketch will have a great in- 
fluence upon the speed and skill that may be attained. From 
the start system in the methods of working should be practiced. 
No one can become expert at sketching unless the habit of 
working systematically is acquired. 

CLASSIFICATION OF SKETCHES. 

The name given usually indicates the nature of the sketch. 
There are two general classes of military sketches: (1) Area 
sketches; (2) reconnaissance sketches. 

Area sketches are classified as : 

1. Position sketch. This is a sketch of an area to all parts 
of which the sketcher has access. Scale usually 6 inches to the 
mile ; V. I., 10 feet. 

2. Outpost sketch. In this the sketcher travels along and in 
rear of the outpost line sketching the area to the front. Scale 
6 inches to the mile ; V. I., 10 feet. 

3. Place sketch. The sketcher is located " in one place " on a 
hillside or hilltop in a restricted area, from which he sketches 
the area to the flanks as well as to the front. Scale 6 inches. to 
the mile ; V. I., 10 feet. 

Reconnaissance sketches are classified as : 

1. Road sketch. This is usually made mounted. The sketcher 
preceding the column sends back his reconnaissance sketches as 
promptly as possible,' so that the commander may use the in- 
formation contained in them on the march and in making his 
dispositions. Scale 3 inches to the mile ; V. I., 20 feet. 



14 SKETCHING METHODS. 

2. River reconnaissance sketch. This is usually made with the 
idea of securing a special report of topographical features and 
other features on a river line. Many of these can not be shown 
by conventional signs and are written on one side of the sketch. 
These sketches are made mounted. Scale 3 inches to the mile; 
V. I., 20 feet. 

3. Railroad reconnaissance sketch. Similar to the reconnais- 
sance of a river. Scale 3 inches to the mile ; V. I., 20 feet. 

OUTLINE FOR BEGINNER. 

The following is a general outline of the successive steps that 
may be taken in learning to sketch. It is inserted here merely as 
a guide to those who are taking up sketching alone or in com- 
pany with others who are also beginners. The time available 
to the student must be used to tJie greatest advantage, and he 
alone is able to divide it with that in view. For this reason the 
steps are merely advisory. All indoor practice suggested should 
be taken up and carried on simultaneously with field work. 

In sketching, as in any other art, practice only makes i)erfect. 
The steps to be taken by the beginner may be analyzed as fol- 
lows: 

1. Study the conventional signs and practice same (p. 21). 

2. Lay ofE a measured ground course and practice striding and 
counting strides (double paces) (p. 17). 

3. Practice making titles for different classes of sketches 
(p. 26). 

4. Determine stride and construct or select scale of strides for 
6 inches to 1 mile and paste on ruler (p. 27). 

5. Take out board and practice orienting by turning arrow to 
north and by backsighting (p. 16). 

6. Practice location of points by traversing and intersection 
(p. 32). 

7. Practice estimating horizontal distances in imits of 100 
yards (p. 33). 

,8. Practice estimating vertical distances in units of 10 feet 
(p. 34). 

9. Run a traverse for a short distance, putting in horizontal 
detail only. Practice locating points by traversing, intersection, 
resection, and estimation (p. 32). 

10. Take up study of contours and practice logical or me- 
chanical contouring (p. 38). 



SKETCHING METHODS. 15 

11. Keep up practice in malving conventional signs by drawing 
imaginary countrysides (p. 24). 

12. Run a traverse again as in figure 9. Practice estimating 
differences in elevation between critical points and noting same 
(p. 40). 

13. Make two or three such traverses, practicing to acquire 
speed and method in your system of working (p. 43). 

Fill in only flat or horizontal detail but be particular to 
locate the drainage lines. Practice orienting by back sight and 
checking each time by arrow pointing to north. Put a title on 
each before considering it finished (p. 46). 

14. Select an area i to 2 mile square and make a sketch of 
it. Practice adjustment to close (p. 45). Show all drainage 
lines clearly. 

15. Meanwhile, having practiced logical contouring until you 
can do it intelligently and rapidly, sketch the same area again 
in the same manner as before, and in addition estimate and de- 
termine elevations of critical points. Now take this sketch 
and contour it by logical methods (p. 39). Do this at home 
or at some place from which you can not see the ground you are 
contouring. The idea of this is to impress upon the beginner the 
necessity of securing all data that may be needed for contouring 
upon one traverse over the ground. 

16. Make another sketch of the same area. Fill in flat detail 
as you go and note elevation and location of critical points. 
When you have the drainage system clearly plotted, contour the 
sketch on the ground. Space the contours according to the 
ground (p. 41). 

17. Make position sketches of other areas in the same manner 
as the last one (p. 45). Never start contouring until the drain- 
age system is " pinned down " ; the big features will then be 
seen, and the little ones will take care of themselves. 

18. Make at least three outpost sketches and two place 
sketches at 6 inches to the mile and 10 feet V. I. before attempt- 
ing to make a road sketch (p. 46). 

19. Construct a scale of strides for 3 inches to the mile and 
take up road sketching dismounted (p. 48). 

20. Secure a mount and make a scale reading minutes for trot 
and walk. Take up mounted road sketching (p. 50). 

21. Later take up other kinds of reconnaissance sketching 
(p. 51). 



16 SKETCHING METHODS. 

SKETCHING TOOLS. 

Sketching board. — The issue sketching board with a com- 
pass set in a trough in one edge is a good board for sketching. 
It has an attachment on the under side for securing the tripod 
to It. It is about 13 by 14 inches, which allows 2 miles of posi- 
tion sketch (6 inches to the mile) to be made with enough extra 
space to secure the paper to the board. 

A homemade board of the same size, made of light wood 
about seven-eighth inch thick, with holes . in two diagonally 
opposite corners for a rope by which to carry it, makes a very 
good sketching board. 

A tripod may be used, but is not necessary. When instructing 
large classes by intensive methods the compass, pace tally, and 
tripod should not be used, as it requires too much time to learn 
their use. 

TO ORIENT THE BOARD. 

Having tripod and compass. — Set up the tripod with board 
loosely screwed on to it and level by eye by moving the tripod 
legs. Note that tripod legs are firmly set so as not to slip 
easily. Free the needle by turning the cam and then turn the 
board slowly around until the needle swings from side to side 
in the trough. Let the needle settle, turning the board so that 
when settled the needle lies directly over the north line in the 
bottom of the trough. Without changing the position of the 
board, reach under and tighten up the screw of the tripod. Care 
must always be taken not to turn the tripod screw too tight, as 
the threads are likely to be started by rough treatment. The 
board is now oriented. Draw a line parallel to the needle on 
the paper and mark the north end with a half arrow. This 
magnetic meridian line is sometimes marked M. M. 

Without compass and tripod. — Draw a line parallel to the 
edge of the paper and place a half arrow on one end of it. Turn 
the board around until the arrow points north and the board is 
oriented. Use watch and sun or general knowledge to determine 
north at first ; thereafter orient by backsight, but check back- 
sight orientation when necessary by the same methods. 

To orient tJie board by backsight. — Having plotted (located 
and drawn in) a station and arrived at a point farther on, 
which you have sighted and drawn a line to, measure off the 
number of strides taken between the two points on your line 



SKETCHING METHODS. 17 

and stick a pin in tlie point found. Tliis is your present posi- 
tion. Place your ruler against the pin and along the line be- 
tAveen the two points, and turn the board until the station 
which you have just left is sighted. The board is oriented. 
Verify this by checking arrow or reading the compass needle. 

All of these methods of orientation can be practiced in a 
small space. Set up the board and orient by compass. Stick a 
pin in your assumed position and draw to a fence post or any 
object 15, 20, or 100 feet distant. Now move over to near the 
fence post and set up again. Orient the board by arrow and 
then verify by a backsight orientation on the first station. For 
this practice a scale of an inch to a few feet may be assumed 
and the distances measured. In this case practice may be had 
from one point to three others and then back to the first. This 
will give an opportunity to check the accuracy of your orienta- 
tion by seeing how well your lines close. Intersection and resec- 
tion methods may also be practiced in this same manner. 

Tally regUter or pace tally. — This instrument is used to keep 
the record of the number of strides (double paces) taken in 
measuring the distance between points. It is important that the 
number of strides be counted as accurately as possible, and for 
this reason the beginner should learn to register them auto- 
matically ; that is, without giving the act of pressing the lever 
any attention. 

With the pace tally held in the left hand, finger through ring, 
the lever is pushed down each time the right foot strikes the 
ground. This system of recording the strides is the best pos- 
sible, because the left hand is free to handle the register and 
after practice will automatically or subconsciously press the 
lever when the right foot strikes the ground, which occurs when 
the left hand reaches the forward point of its swing. The more 
nearly automatic the act of recording the strides becomes, the 
more can the sketcher's attention be given to observing the con- 
figuration of the ground and the details of the country through 
which he is passing. 

However, it is possible to get very good results by training 
men to count their strides and tally every 100 strides on the edge 
of the paper. There are various ways of counting and tallying 
strides without a pace tally. After a little practice each indi- 
vidual will select his own way. The beginner should learn to 
stride at a uniform gait and to register the strides or to count 
them with the least mental efEort. Do not attempt to take 
20171°— 17 3 



18 SKETCHING METHODS. 

strides of a certain lengtli, but step along at a natural gait, 
swinging the arms naturally and keeping tlie mind off of the 
counting of strides or of their length. When walking anywhere 
by yourself practice counting your strides or carry the pace tally 
and register them. If opportunity offers do this in walking to 
or from your office or place of business. Practice it as much as 
possible, and you will soon find that the number of strides in a 
given distance will become more and more uniform. Until one 
learns to stride naturally and uniformly the stride will be 
affected by walking with or near another person. 

Once in a while a tally register will be found which occa- 
sionally fails to register a change of 100 strides. This can be 
detected by a peculiar click when it happens. The failure is 
often due to the sketcher not pressing the lever down far 
enough. The register can be tested indoors by watching the 
face of the dial while pressing the lever and tallying through 
a couple of hundred counts. 

M^ * * 6in ^ Imi. * '° «2in.8ts 

^ tlllinilliillii i ili i nliii i lmiliiiiliiiin i liliiiL i ii l 

Fig. a 

Triangular ruler {fig. 2). — The best ruler for sketching is one 
of triangular shape about 8 inches long with faces about 0.8 
inch wide, with both ends weighted. Such a ruler has been de- 
veloped at the Army Service Schoois and can be bought at slight 
expense from the Book Department, Army Service Schools, Fort 
Leavenworth, Kans. It has on it a scale of inches, one of 100 
yards at 3 inches to the mile, and one of 100 yards at 6 inches 
to the mile. There is ample space left on which the sketcher 
may paste his scale of strides for sketching at 6 inches and at 3 
inches to the mile, as well as his horse's walk and trot scale 
for mounted work. A very satisfactory ruler can be made by 
sawing in two a piece of pine or other common wood about 
seven-eighths inch square. This makes a triangular ruler which 
is convenient in size and shape. It should be cut in 6-inch 
lengths and should have on it the sketcher's scale of strides, a 
scale reading 100 yards at 6 and at 3 inches to the mile and an 
inch scale reading down to a tenth of an inch. 



SKETCHING METHODS. 19 

When using the ruler for sighting an object, place one of the 
edges against the pin in your station, sight along the top edge, 
and pivot the ruler with forefinger and thumb around the pin 
until the desired object is in line. Then draw the ray (light 
line) along the edge of the ruler next to the pin. When sighting 
up or down a steep slope, the sketcher may find it of assistance 
to stick a pin vertically in each end of the top edge and use them 
to sight by. 

Pencils. — A soft pencil, HB grade, or Eberhard Faber No. 2 
with eraser on it, should be used in learning to sketch. Harder 
pencils will tear the paper, and their marks are so difficult to see 
that the sketcher is likely to strain his eyes. When sheet cellu- 
loid is used, a 2H pencil is better. 

A knife or a pencil sharpener should be carried, and the pen- 
cils should always be kept sharp. A piece of emery paper pinned 
to the carrier is very valuable for putting on a finished point. 

Eraser. — A soft rubber eraser is a popular article in the equip- 
ment of the beginner. The Ruby, Eberhard Faber, New York, is 
a very satisfactory one. One on the pencil will serve, however, 
very nicely. 

Paper and thtmib tacks. — All sketches should be made on a 
tracing paper in order that they may be blue printed without 
the necessity of tracing them. For this reason tracing paper 
should always be used, except in the earlier practice when any 
variety of drawing or heavy wrapping paper will do. It will 
be found that the paper, if pinned to the board by thumb tacks 
some time before it is to be used, will bulge up and have to be 
readjusted. For this reason it is v\^ell not to pin your paper 
in position until just before starting out. Extra thumb tacks 
should be carried. These may be stuck on the under side of the 
board or kept in a piece of cork in the carrier. 

Large-headed pins. — Several of these should be stuck in the 
carrier or clothing where they can be gotten at conveniently. 
They are most useful in sketching. Common glass-headed pins 
about 1^ inches long with a head about one-tenth inch in diam- 
eter are best. 

Carrier. — This can be made of canvas or heavy cloth sewed 
over a piece of light wood or heavy cardboard, or they may be 
purchased at the Book Department, Army Service Schools 
(fig. 3). The sketcher must have every appliance in its place 
when he wants to use it, and the carrier offers a most con- 



20 



SKETCHING METHODS. 



venient place for nearly all of his tools. The carrier, however, 
is not necessary. 

Stop watch and note pad for mounted tcork {fig. 4). — These 
are very convenient for mounted work. The pad is divided into 
blocks. The middle line from the bottom up represents the 
sketcher's route by minutes and quarter minutes of travel, while 
the horizontal lines to the sides represent hundreds of yards 




p 


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Z4 


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fig-/ 



off from the sketcher's route. As the horse trots along the 
road, the sketcher jots down on the pad in their proper places 
the various features which he observes. After some minute^ of 
travel, he dismounts, and, using these notes, sketches in the 
road over which he has passed. It is well in making notes on 
the pad to use a blue pencil for noting water courses and hori- 
zontal details and a red one for carrying along the elevations. 
A pencil with red at one end and blue at the other can be pur- 
chased at any bookstore. 



SKETCHING METHODS. . 81 

CONVENTIONAL SIGNS. 

The conventional signs used in military sketching are illus- 
trated in Field Service Regulations. 

In practical sketching, if it is more difficult or requires more 
time to make the conventional sign than it does to write what 
is meant, the experienced sketcher will write the description. 

A sketch is made primarily to convey certain information. 
If what is meant to be conveyed is not clear the sketch is of 
no use. Again, if it takes a commander too long to read a 
sketch he will blame the sketcher, and as his time will probably 
be valuable he may not be able to take time to read it. Always 
remember that the sketch is being made to be read, that the 
convenience of the reader is sought, not that of the sketcher, 
tliat it is useless to put a mark on the sketch unless that mark 
has a meaning which the reader will be able to make out. 

It is desirable that the conventional signs shall picture what 
they represent as nearly as possible, so as to be easily inter- 
preted ; be simple in construction so that they may be made 
rapidly ; not take too much space on the sketch ; and that they 
be so clear as to be readily understood and not be mistaken 
one for another. 

Practice in rapid work has developed many short cuts in 
making them. These convey the same information with fewer 
pencil marks and probably greater clearness (fig. 5). 

It is to be noted that the cross marks on a railroad, the 
signs indicating the different kinds of fences, the marks along 
a road indicating telegraph line and the T representing a tele- 
graph line across country, are to be made 1 inch to IJ inches 
apart on a scale of 3 or 6 inches to the mile. This is done prin- 
cipally for the sake of clearness, though a great deal of time 
is saved by it. It is, however, an excellent rule never to put 
a mark on a sketch, no matter how small, that is not necessary. 

A culvert or bridge less than 10 feet long (road length) should 
be represented by two V's at right angles to the road, with the 
points of the V's opposite each other. Dimensions need not then 
be given as in a larger bridge, but the material and the condi- 
tion, if poor, should be noted, " brick, poor," or " wood, bad." 

Roads are conventional signs. Try and show^ them about one- 
sixteenth of an inch wide at 3 inches to the mile and about one- 
tenth inch wide at scale of 6 inches to the mile. The road 
lines should stand out clear and distinct, with no lines or other 



^ 



SKETCHING METHODS. 



conventional signs crossing the road. Fence and telegraph signs 
are placed on the road lines. 



^ \ Cut lo- / ^^ 
—I H L^ 



KoacL-^Smooth and Bar 
-bedWire Fences. Cut 



. Road. He cLjJe. Fence Tele 
-it-r- — =r-ri — ; 7—}( praph. Fill " 



-y — 



1 ^ 

S.D rfA R K. 
1 1 



^ Culvert. Bridge wiVK 
— Dimensions. 






_, Railroad Kx^^ht of Wa\^ 

Fence rvla\j Be Shown or 

^ Note Sta^in^ it is There 

' M a\| Be Made iy\ Margin . 

Barbed Wire Fence 




Across Countr>j . 
^ Tel. Line Off Road 

Woods \ Area Covered b\j Woods. 



Stream Line So' Wide 
2o'WD 8'Banks 2' Deep. 
6:b.2'd. ScatteredTrces on a\l 
3u,t OT\e Branch 
Broken Line s no Water 



Orcl^ayrf 



o o o o o 
o o o o o 



.: Cult. { \ Corn- 



I House 6 
Jiouse 3 



Stone 

'-1 Mile r 
>-lMile L 



Brushj 



Where Area i5 
•Not Cultivated 
Leave "Blank. 



Conventional Signs 



A hedge fence is represented by drawing H's across one of the 
road lines at about the same intervals as fence signs. Fence and 



SKETCHING METHODS. 23 

hedge signs are the only marks that should ever appear between 
the borders of a road. 

Stone and wood fences, being very unusual features, are noted 
in sketching by writing in "stone" or "wood" along a line 
drawn to represent the fence ; if along a road use the road line, 
with marks indicating the limits of the stone or wood fence. A 
marginal note is simplest and easiest. 

Signs for single trees are drawn oblong in shape and about 
one-tenth of an inch long at 6 and about one-sixteenth inch 
long at 3 inches to the mile. Space them sufficiently to be dis- 
tinct so as to blue print readily. Do not attempt to show indi- 
vidual trees. The sign indicates trees in that locality. 

Houses are represented by black blocks which are made square 
and large enough to be set in the road at the scale being used. 
That will make the house sign about one-tenth inch square at 
6 and one-sixteenth inch square at 3 inches to the mile. 

In order to proportion the signs to the scale used it is conven- 
ient to always make the lines that go on or along the road about as 
long as the road is wide. This refers to such signs as a telegraph 
line along the road, the barbed-wire fence lines which make the 
X's on a road line, and the signs for cuts, fills, bridges, cul- 
verts, etc. 

A row of houses occupying a certain distance along a road 
need not be indicated individually, but house signs covering the 
scale distance occupied by them should be drawn in. 

A dry watercourse should be indicated by a broken line, 
which should be wavy so as not to be mistaken for a trail sign, 
which is a broken straight line. If there is a small town along 
your road, do not attempt in a road sketch to show the indi- 
vidual streets, alleys, and houses, but make a town sign cover- 
ing the area of the town, and write in its name. (See fig. 1, 
town of Dover.) 

Where the conventional sign or written words can not be put 
in at the place desired without excessive crowding, write a (1) 
at that place and insert description in a marginal note opposite 
a (1) on the margin. Carry these marginal notes by serial 
numbers ; on a road sketch, start them at the bottom of the 
margin and run up; on other sketches, start at the top of the 
paper and number them down. 

Break contour lines on each side of a road, a conventional 
sign, or an abbreviation (as a description of a bridge). Never 
run them through. 



24 SKETCHING METHODS. 

It should be remembered that your sketch, when finished, 
must be ready for blue printing copies without tracing ; therefore 
all signs should be distinct enough for this purpose. All lines 
should be firm and clear cut. 

Anyone who has the ability to learn to read and write should 
be able to learn to sketch. In sketching, as in writing, how- 
ever, the signs used have to be learned, and facility in making 
them has to be gained before much can be accomplished. Much 
time is wasted in the field by beginners on account of the fact 
that they have not sufficient familiarity with the conventional 
signs and abbreviations to enable them to put down the right 
one quickly. No one should attempt to sketch until the conven- 
tional signs are learned and some facility in making them has 
been acquired. This can be practiced anywhere indoors by 
drawing a skeleton sketch of roads and stream lines and filling 
in imaginary countrysides. Locate and draw in farmhouses, 
orchards, fences, trees, woods, cuts, fills, bridges, unimproved 
roads, railroads, etc. Form a general idea of scale distances, but 
make this practice mainly to help you to learn the conventional 
signs so that when you see something that you wish to repre- 
sent, you will be able to put it down without having to stop and 
think how you should represent it. It is splendid practice for 
a class to have the instructor dictate to them a description of a 
countryside which the students represent by conventional signs 
at the scale ordered. The various features and objects are rep- 
resented according to the distance and direction as given by 
the instructor. To stimulate interest and note progress the 
papers may be turned in and corrected. It is not only neces- 
sary to know the sign when you see it, but it is necessary in 
sketching that you be able to make it quickly and easily. It 
should be easier for the sketcher to make the conventional sign 
than to write the words. Practice of this kind will also assist 
in overcoming the diffidence that many feel about the mechanical 
work of drawing, as it will accustom the hand and eye to work- 
ing with pencil and ruler. 

A familiarity with the scale distance of some commonly used 
unit of measure is essential to the sketcher for putting down 
distances as he estimates them. All estimates of distance 
should be made in hundreds of yards ; therefore the sketcher 
should be able to accurately lay off a 100-yard measure to the 
scale of the map. As all work in learning to sketch will be at 
6 and 3 inch scales, the beginner should practice, along with 



SKETCHING METHODS. 25 

the making of couveutional signs, jotting down hundreds of 
yards at 6 and 3 Inches to the mile and inclies and halves and 
tenths of inches. This can be done by dotting off these dis- 
tances any time or anywhere and then checking them with 
those found on the triangular ruler. This also gives an idea of 
what may be shown at the different scales. At scale of 1 inch 
to the mile a heavy pencil line is about 50 yards wide; one- 
tenth inch at 6 inches to the mile is about 30 yards ; at 3 inches 
to the mile it is 60 yards ; and at 12 inches about 15 yards. 
This practice is most important for the beginner. 

TITLE. 

Every completed sketch should contain a title, setting forth 
the character of the sketch, the sketcher's name and rank, the 
locality sketched, the date, the scale (in inches to the mile), a 
graphic reading scale of yards, and the north and south line 
parallel to one side. 



Position Sketch 


Near Easfon 


By W^SmH-h.Capi-. B^'^/nf 


May 15 19/5 


6" = /m/7e 


Yards 


lOO <> (OO ?00 30O M>0 500 600 700 800 





Fig. 6 

All lettering on position sketches should be written so as to 
be read from the south edge. In place sketches it should be so 
located as to be read from the sketcher's position with the 
sketch oriented. In outpost sketches the lettering is read fac- 
ing toward the enemy. In road sketches the lettering should 
be made so that it may be read by anyone following the route 
of the sketcher with the sketch oriented. 

Figure 6 illustrates the title for a position sketch. In another 
kind of a sketch the proper name and scale is substituted. 
20171°— 17 4 



26 SKETCHING METHODS. 

Printed letters are so much clearer than ordinary longhand 
writing that they should always be used in the body of the 
sketch and, where time permits, in marginal notes. In recon- 
naissance sl^etches there will be so many marginal notes that 
it is usually impracticable to print them and they are therefore 
written out in longhand. 

Contour numbers should also be placed, as far as possible, 
the same as the lettering. See figures 10 and 11. 

Time is saved and the chances of omissions avoided by blocli- 
ing out on heavy cardboard a completed title like the one in 
figure 6, and keeping it in the back part of the carrier. This 
can be slipped under the paper on the board and traced. 

In a road sketch put the title at any convenient place. In 
all other sketches place it so as to be read from the south 
edge. 

Where the V. I. used is different from that prescribed in the 
normal system of scales (p. 34), it should be noted in the 
title. 

SCALES. 

It is usual in military work to speak of the scale of a map 
or sketch by stating the number of inches on it, which repre- 
sent 1 mile on the ground. Thus we say a certain sketch is 
made on a scale of 3 inches to the mile, meaning that 3 inches 
on the sketch represents 1 mile on the ground. 

A scale may be expressed in three ways, any one of which 
is sufficient to acquaint the reader with it. These three ways 
are: 

1. By expression in words and figures : 3 inches equal 1 mile, 
6 inches equal 1 mile. 

2. By what is known as the " representative fraction." This 
is abbreviated as " R. F." The fraction expresses map distance 
in its enumerator and corresponding ground distance in its 
denominator. For example, the R. F. of a map on a scale of 
3 inches to the mile would be written R. F. =-2TTrG- The 
numerator is always reduced to unity. One (unit of measure) 
on the map represents 21,120 (of the same units of measure) 
on the ground. The scale in inches to the mile is readily 
found by dividing the denominator, 21,120, into the number of 
inches in a mile, 63,360. This scale is seldom used in sketching. 
Its use is mainly in case of making a sketch which may be 
converted into some foreign unit of measure. 



SKETCHING METHODS. 27 

8. By a graphic scale. This is a Hue drawn on the map or 
sketch and divided into equal parts. Each of these is marke-V 
with the number of ground units it represents. In our ser^ic^ 
it is usual to make these divisions read miles and halves and 
quarters of miles when expressing the scale graphically. This 
scale is useful on maps which are to be increased or reduced 
by photography, on account of the fact that it will always read 
true. 

There are two other kinds of graphic scales — reading and 
working. The reading scale is made to read some well-known 
and commonly used unit of measure, as feet, yards, etc. In 
military sketches it is made to read yards. To construct a 
reading scale at a scale of 6 inches to 1 mile, lay off a couple 
of inches of length and divide each inch into three parts. Each 
part will then represent 100 yards. At that scale 0.346 inch 
represents 100 yards, and that is as near one-third of an inch 
as it can be drawn with an ordinary pencil. After dividing the 
inches into thirds divide the left division into four parts, each 
of which will represent 25 yards. Mark off the main scale to 
read hundreds of yards. For sketching purposes 1 mile may 
be said to contain 1,800 yards. At scale of 6 inches to 1 mile 
1 inch will equal 300 yards and one-third inch will equal 100 
yards. 

The working scale is made to read the units of measure used in 
making the sketch. In sketching this is usually strides (double 
pace) for dismounted work, and minutes of travel of horse ^t 
trot and walk for mounted work. The completed military 
sketch should contain the scale expressed in words and figures, 
as 6 inches=l mile, and a reading scale to read hundreds of 
yards. The working scale should not appear on the sketch. 

It is not essential that the sketcher should have to do the 
mechanical drawing in connection with the consti-uction of his 
working scale. He should know how to do it in case of need. 
Scales for any length of stride or minute scales for a horse at 
trot and walk at any desired scale can be secured from the 
Book Department, Army Service Schools, at Fort Leavenworth. 

Stride scales for 6 inches to 1 mile are printed in figure 7. 
They are placed here for convenience. To use one of them the 
sketcher must first carefully determine the length of his stride 
and either cut out the scale for his length of stride or lay off 
the divisions on another paper and paste on his ruler. Assume 
that the average number of strides taken by the sketcher over 
a 1-mile measured course is 1,048. To determine the length of 



28 SKETCHING METHODS. 

stride divide 03,360 (the number of inclies in 1 mile) by 1,048, 
and the quotient, 60.4, will be the number of inches in one 

Fig. 7 

12 3 inclie.s 

1 I 1 i 

SCALE OF STRIDES 
6" = 1 MILE 

M"i"iil[mi|iiMM iii|iill[in i|iiiiJi linniUlMIl ""Ml. 
60 Inch Strides 2 4" 

['l.l| iiii[illl|iiillllli| II ll|llll[lUljl llllllll|llliillllll I 
^ 61 Inch Strides 2 4k O 

I'l ii|iii i|ii II |nnn III |i I mil ii|iiii |ii II n iii|i II mil i|i 

^ 62 Inch Strides 2 4 6 

'" Mf Mil |ll I I |lll Ml I II |llll [t|ll|ll ll |M II |MI l|lll I III 111 

^ 63 Inch Strides 2*4 6 

II I M I MM l| 11 II MM ill II I III I [lllllllll I II I Ml Ml |l . M I M M 
^ 64 Inch Strides ^ ^ 

1 I II ' I 111 I |l I I I I I I I III 11 I I I II r|l nil II HI I I II II III I I I I lU-i 
65 Inch Strides »- ^ 

n.i mil 1 1 1 111 I III ii|iirii iii!| III Mill I 111 I iiii I |i II I 111 

*' 66 Inch Strides ~ ^ 

11 I II I MM I I I M |lll M ill I |M I I [11 II 111 llj IN I I I l l l|ll l I II 
^ 67 Inch Strides "^ "* 

Ml I I I I I I I I I I I I I I I I III I I I I I I I I [M II I I I 1 Ij I II IJLI I I I 1 1 I I I 
68 Inch Strides " ■* 

I ilil|llll[lllijllll l llil|lll l[lilimi ljlt lllll ll [ IJJ-L 
^ 69 Inch Strides 

|M I I I I I I I I I I I I I 11 I I |l III |lt I I I I m I II I I I 1 II II I I M I I I I I 
70 Inch Strides 2 4 

stride. Select the scale reading nearest to the length found. In 
this case 60 inches would be taken as the stride. 



SKETCHING METHODS. 29 

Scales constructed by the student should be made in ink and, 
when dry. pasted on to the ruler and later given a coat of shellac 
to make them waterproof. 

It is very important that the sketcher develop a uniform stride 
and that the strides be accurately counted. To accomplish this 
is the most difficult part of scale making. The average number 
of strides over a given distance must be fairly uniform, or the 
working scale, no matter how accurately constructed, will not 
be of much use. 

Every sketcher must have a working scale, constructed to read 
strides, at 6 inches to the mile. Later, one at 3 inches to the 
mile for practice In road sketching should be made, and when 
mounted work is taken up, a scale reading minutes and fractions 
of minutes of travel of the horse at trot and walk at 3 inches 
to the mile will be needed. 

The making of a scale for working purposes is simple and 
easy enough if it be kept clearly in mind that it is merely a de- 
termination of the length that will be required to show a given 
number (usually 100) of strides on the ground at the scale 
desired. 

To make a working scale of strides at 6 inches to the mile, 
measure off with chain or tape a ground course along a road or 
preferably across country " over hill and dale " of 1 mile, three- 
quarters of a mile, or one-half of a mile. The longer the course 
the better. It should be over average ground (up and down hill) 
similar to that which is to be sketched and should be carefully 
measured. 

Walk this course both ways several times, counting strides 
with the tally register as described under " Tally Register," or 
by counting and tallying every 100 strides with paper and pencil. 
Do this on different days and at different times of day. 

When it is found that the number of strides required to trav- 
erse the distance is fairly uniform, take the average of the 
last half dozen trials to determine your average for that distance. 

In any method of constructing a scale the above steps must be 
taken. The further proceedings in the actual laying off and 
marking off the scale may be accomplished in several ways. 
Two ways considered the simplest and easiest are given here. 

The first method is to lay off on your paper the scale distance 
in inches of the course and divide it into as many parts and 
fractional parts as you have hundreds and fractions of hundreds 
of strides in your average. 



30 SKETCHING METHODS. 

Each full division will then show the length on the Avorking 
scale that will represent 100 of your strides at the desired scale. 
The fractional division will represent an odd number of strides 
and may be erased, as there is no need for it. 

As an example, assume that you find the average number of 
strides to cover a measured 1-mile course is 1,048. Lay off a 
line 6 inches in length (the scale distance for 1 mile) and divide 
it into 10.48 equal parts. 

Each full division will show the distance on your working 
scale which is required to represent 100 of your strides at a 
scale of 6 inches to the mile. 

To complete your scale, divide the left one of the 100 stride 
divisions into 10 equal parts. This part of the scale is called 
the extension and is made in this way for convenience. Each 
of the 10 parts in the extension represents 10 of your strides. 
Mark the dividing line between the extension and the main 
scale as zero and then each dividing line along the main scale 
between the other parts with the number of hundreds of strides 
it measures from the zero mark. 

It should be remembered that when this method is used the 
line to be divided in making a scale corresponding to 6 inches 
to the mile must be the same proportional part of 6 inches that 
the course on which the average number of strides was se- 
cured is of 1 mile. That is, if the course is 1 mile, lay off 6 
inches; if it is three-fourths of a mile, lay off (three-fourths of 
6 inches) 4* inches; and if the course is one-half mile, lay off 
(one-half of 6 inches) 3 inches. 

The second method is to ascertain the length in inches or 
fractions of an inch which will represent 100 of your strides. 
Having this, lay off the number of divisions of that length de- 
sired, mark them and paste them on the ruler. For example: 
Assume that the average number of strides to 1 mile is 1,048. 
It is desired to construct a working scale at 6 inches to 1 mile. 
Divide 6 by 10.48 and the result (0.572 inch) will be the length 
on your working scale which will represent 100 of your strides 
at 6 inches to 1 mile. 

With a scale of equal parts (one reading inches and tenths 
of inches will serve), lay off as many divisions 0.572 inch long 
as you may desire in your scale, and each of them will repre- 
sent 100 of your strides at 6 inches to the mile. Mark off the 
extension and the main scale as previously described, trim to 
suit, and paste on rulex*. 



SKETCHING METHODS. 31 

When a scale of strides for 6 inches to the mile has been 
made, all that is necessary to construct one at 3 inches to the 
mile is to take off on a piece of paper the divisions on the 6-inch 
scale and mark them with just twice the value they have at 
the 6-inch scale. Each division of the extension will represent 
20 strides at 3 inches to the mile. 

Either of the foregoing methods may be used in constructing 
a time scale for a horse. It is first necessary that the horse 
should be trotted and walked several times over a course and 
his average time of travel secured. In doing this care should 
be exercised that the horse's gait is not influenced by the pres- 
ence of another horse, the fact that the animal is tired or 
fresh, that he is going toward or away from the stable, etc. 
Allowances must be made for such things, and practice enough 
should be had, before constructing the scale, to enable the 
sketcher to determine pretty well whether or not the horse is 
taking a uniform gait. 

Working scales should be tested from time to time by the 
sketcher in order to be sure that his stride is not changing. 
This can be done by occasionally checking traverses with a 
Geological Survey map or by measuring with chain and tape 
some of the distances traversed. 

WHAT A SKETCH SHOULD SHOW. 

Broadly speaking, a military sketch should show all natural 
and artificial features of the surface of the earth in the area 
sketched. The magnetic-meridian line, a title giving the char- 
acter of the sketch, the locality sketched, the date, the 
sketcher's name, the scale of the sketch, and a graphic scale 
reading hundreds of yards should also be shown. 

Natural features (bodies of water, woods, etc.) and all " works 
of man " are represented by conventional signs, drawings to 
scale, or by written words. 

The configuration of the ground is represented by contours 
showing elevations and depressions with the character of their 
slopes and relative heights as truly as the scale of the sketch, 
the time allowed, and the sketcher's ability will permit. 

All detail, except that shown by contours, is called flat or 
horizontal detail. That shown by contours is called vertical 
detail. The military sketch must have every feature located 
in its relative horizontal and vertical position. 



32 SKETCHING METHODS. 

HORIZONTAL DETAIL. 

The horizontal position of any point is determined when its 
direction and distance from a previously determined point are 
shown. The vertical position is determined when its elevation 
with reference to an assumed level, called a datum plane, is 
shown. 

The line from which all directions are measurd is the plane 
of the magnetic compass needle, called the magnetic meridian. 
The true north and south line (true meridian) need not be con- 
sidered in sketching. It is most important wlien direction lines 
from one point to another are located that the sketching board 
be oriented (explained under "Sketching Board"). The 
sketcher should therefore always verify the position of the 
needle or of the arrow on his board before drawing a ray (light 
line) toward the object whose direction is being determined. 

The position of a point, with reference to direction and dis- 
tance, is determined in one of the following ways : (1) Travers- 
ing; (2) intersection; (3) resection; (4) estimation. 

TRAVERSING. 

By this is meant the measurement of the distance between 
two points by counting the strides or time of travel required to 
pass from one to the other. 

The term traverse is applied to the route followed by the 
sketcher in making the sketch. 

To locate a point by traversing. — Being at point A (whose 
position is plotted on your sketch) with the board oriented, 
stick a pin in point A, on the sketch. Lay ruler alongside the 
pin and pivot it around until point B (the point to which you 
are to traverse) is sighted. Verify the position of the arrow 
and then draw a ray toward B. Move to B, counting strides, 
and upon arrival lay your ruler along the ray with the zero 
of scale of strides at A and lay ofC on the ray the number of 
strides that you took between the two points. The point 
marked is B. 

INTERSECTION. 

The position of a point is determined in this method by draw- 
ing rays toward it from each of two other points, whose posi- 
tions are already determined and plotted on the sketch. The 
intersection of the two rays is the sketch position of the point 
sighted. 



SKETCHING METHODS. 38 

To locate the position of a point by intersection. — Assume 
that from point A, with your board oriented, you took a careful 
sight and drew a ray toward a church a few hundred yards off 
to the side. After arriving at B and plotting its position, you 
carefully orient the board by a back sight on A. Pivot the ruler 
around the pin in B until the church is sighted, then draw a ray 
toward the church. The intersection of this ray with the one 
you drew from A is the sketch position of the church. 

RESECTION. 

This is determining the sketcher's position by orienting the 
board and drawing rays toward himself from two or more 
points whose positions are already determined and plotted. 

To locate position by resection. — After having plotted the po- 
sition of points A and B, the sketcher comes into his area later 
at some point from which those two points can be seen. His 
present position is not yet determined. To determine it, set up 
the board and orient as carefully as possible by the arrow, then 
stick pins in the sketch positions of points A and B. Pivot the 
ruler around the pin at A on the sketch until you sight A on the 
ground and after verifying the position of the arrow, draw a 
ray toward yourself. Next pivot the ruler around the pin at B 
on the sketch until you sight B on the ground, and after glanc- 
ing at arrow, draw a ray from that point toward yourself. The 
intersection of the two rays is the sketcher's position. 

There are other methods of resection, but their use is so ex- 
ceptional that they need not be considered. 

ESTIMATION. 

After some practice, points nearby are located very accurately 
by simply estimating their distance and plotting their position 
on a ray drawn toward them. Advantage is taken of any fea- 
ture in the locality that may assist in determining the distance, 
such as telegraph or telephone poles, fence posts, section lines, 
etc. The ability to estimate distances should be cultivated at 
every opportunity. A good sketcher must be able to estimate 
with less than 10 per cent error up to about 300 yards and 
within 20 per cent up to a mile. This ability can only be ac- 
quired by constant practice and by verifying the estimates by 
measurements. All estimates should be made in yards, and 100 
yards should be definitely fixed in mind as a reference unit. 

Do not estimate on main traverse. 



84 SKETCHING METHODS. 

VERTICAL DETAIL. 

The United States Geological Survey uses sea level as datum 
plane in determining elevations of points. 

In military slvetclies the area is comparatively so small that 
the datum plane used is immaterial. The reason for this is 
that M^hat is desired is the elevation of the different points in 
the area with relation only to the other points in it. It is im- 
material whether the elevation of the starting point is assumed 
to be 500 feet or 1,000 feet, but all other points must then show 
their elevation with reference to the assumed one. 

It is well to ascertain the Geological Survey elevation of 
some point and start from there, because the sketch can be 
checked against a Geological Survey map more conveniently 
when the elevations are the same, but it is not at all necessary 
that this be done. 

Under our normal system of scales the vertical interval 
(V. I.) used on military maps and sketches can be found by 
dividing the number of inches representing 1 mile in the scale 
into 60. For example, at 6 inches to 1 mile the V. I. is 10 feet. 
At 3 inches it is 20 feet, and at 12 inches to 1 mile the V. I. is 
5 feet. 

The vertical position of a point is located by determining its 
elevation above or below some other point whose elevation has 
already been determined. 

The determining of difference of elevation of two points by 
estimation is the method of the experienced and rapid sketcher. 
After some time and with considerable practice the sketcher 
acquires ability to estimate differences with great accuracy. 

There are many ways in which practice in estimating eleva- 
tions may be had. The ability to strike one's own level is of 
great value. This can be practiced indoors by swinging the 
extended arm around with the hand at level of the eye, so 
that the line of sight over the back of the hand passes through 
marks made upon the wall at the exact height of the eye. 

Having learned to strike your own level, practice estimating 
distances or objects above and below this plane by comparison 
with the heights of ordinary objects in the vicinity, such as 
telegraph poles, trees, etc. Fix in mind a 10-foot unit and apply 
this to the height being determined. 

In connection with estimating either horizontal or vertical 
distances it is well for the beginner to remember that it is 



SKETCHING METHODS. 36 

fatal to good estimation to depend upon liis judgment until he 
has a definite and clear idea of what the units of measure he 
is using really are, and hence he should if possible check all' 
estimates until he has attained the ability to estimate with a 
minimum of error. This will come only with practice and con- 
stant checking. 

CONTOURS. 

The representation of vertical distances by means of con- 
tours seems hard to the beginner. This is largely due to the 
fact that the average beginner usually attempts to contour be- 
fore he really knows what a contour is, what lavfs govern their 
making, or what may be shown by them at the scale being used. 
Before attempting to do any contouring in the field the begin- 
ner should gain a clear idea of these things by careful study 
and much practice, so that when he takes up contouring he will 
know what he is trying to do. 

Contours are lines drawn on a map or sketch, which, follow- 
ing the various levels at fixed vertical intervals, indicate the 
shape of the ground and show its vertical irregularities. 

The general laws governing the use of contours may be fully 
learned only by actual field work. Some are noted here : 

1. Every contour line either closes on Itself or both ends of 
it go off the sketch. 

2. Every part of a contour line is at the same level. 

3. A contour about to cross a stream line runs up on one side 
of the stream and comes down on the other, making a V where 
it crosses. The apex of the V points upstream. 

4. Contours representing spurs between stream lines are gen- 
erally U-shaped, with the bottom or rounded part of the U 
pointing down hill. 

5. Valley contours apparently go in pairs ; that is, the contour 
next to the stream line on one side is the same contour as the 
one next to the stream line on the opposite side. If you cross 
the 800-foot level just before you wade into a stream, you must 
cross that same level again when you wade out on the opposite 
side. 

6. Ridge contours also apparently go in pairs. The contour 
next to the top of a ridge has its mate next to it just over the 
ridge. 

7. In the case of the contours on opposite sides of the stream 
their meeting point will generally be found close by; in those 



36 SKETCHING METHODS. 

next to the ridge top it may be tliat they do not join up on the 
sketch, but if tlie area were extended their meeting point would 
be found sooner or later. 

In sketching do not attempt to show a cliff by contours. 
Break the contour lines on each side and write " Cliff 60' " (or 
whatever its height may be). Do the same with a bluff which is 
so high and steep as to make difficult clear representation by 
means of contours. If you have a depression to represent, be 
sure that the contours showing it are clearly numbered, so that 
it may at once be understood. 

DETAIL SHOWN BY CONTOURS. 

The amount of detail that may be shown by contours depends 
directly upon the scale of the sketch. Failure to realize this is 
one of the reasons why the representation of ground forms by 
contours is often difficult for the beginner. For example, on a 
scale of 3 inches to the mile a ,spur 100 feet long jutting out 
from a hillside would cause a contour line to change about one- 
twentieth inch, the scale width of the spur. If trouble were 
taken to change an otherwise regular contour to indicate this 
no one would notice it nor care anything about it if it were 
noticed. It is true that this spur might furnish cover to a num- 
ber of the enemy, but when the commander wants a sketch in 
which such cover becomes important, he will have it made on a 
larger scale. 

The minimum size of ground features that can be shown to 
advantage to the scale used should be determined and kept 
clearly in mind by the sketcher. Then, so far as anything 
smaller is concerned, he should regard the ground as smooth 
and regular. This will greatly simplify his work. 

It must be realized that any details that can not be shown 
clearly and naturally to the scale ordered are not wanted. 
This, of course, refers only to those features that are to be 
shown to scale. Houses, bridges, roads, stream lines, etc., being 
represented by conventional signs are not drawn to scale. 

A good method to follow to gain an idea of what can be .shown 
at the various scales by contours is to take a map or sketch of 
an area and carefully study the ground represented and note 
the smaller details that are not shown on the map. Compare 
map and ground, again noting carefully the ground forms as 
they are on the ground and then how they are represented on 
the map. 



SKETCHING METHODS. 37 

A box filled with sand, called a sand table, is a great aid in 
studying ground forms and may be used if time permits and 
outdoor work can not be done. Many exercises can be held in 
which much can be accomplished in learning how to contour. 
Make a mound, assume a scale, and represent it by contours. 
After drawing in the flat detail of a sand-table terrain, contour 
the area, first determining the elevation of the critical points, 
then spacing the contour points by eye, according to the slopes, 
and then connecting up the levels. 

Take a section of a contoured map and reproduce it on the 
sand table according to scale. Later, without looking at the con- 
toured map, make a sketch of the area and compare it with the 
contoured map. 

Any ground forms can be produced and their contour lines 
studied out and drawn. The amount of work that can be done 
on the sand table depends upon the time the student will give 
to it and his ingenuity. 

The value of the sand table is, of course, limited to giving 
a thorough understanding of ground forms and of their repre- 
sentation by contour lines. This understanding is essential to 
the sketcher. Practical familiarity with ground forms and 
ability to represent them correctly can only be gained on the 
ground, for the only way in which the ground perspective can 
be appreciated is by study of the ground itself. To the be- 
ginner, ground distances appear greater and features near by 
larger than they actually are, and this can only be corrected by 
actual work on the ground. 

LOGICAL CONTOURING. 

The Engineer Department at the Army Service Schools at 
Fort Leavenworth has had printed a number of plates for the 
purpose of practice in drawing contours. These show the flat 
details of the area and the elevations of critical points. The 
entire series should be filled in by every beginner and corrected 
by an instructor before attempting any fieldwoi'k other than 
filling in flat details. The series consists of several sheets, each 
with four areas. These can be secured at small cost from the 
Book Department, Army Service Schools. Too much of this 
practice can not be had. The method of filling in the contours 
is illustrated in figures 8, 9, 10, and 11. 



38 



SKETCHING METHODS, 



Practice in logical contouring, as it is called, is most neces- 
sary to a clear understanding of contouring in sketching. The 



/ 


073 


.867 


fl5<5 


790 / 


' 7 


ei2' 


[876 


^^ 




630 


,\ 


650 


! 


870 '. 


• eeo 


860 


/'' 


asi 


,(, 






/ 






•' ■; 


"89? 




'a''i 


665 



F"'g 8 

Arrow heads on Fig. S show direction of water flow. 
Place 10' contours on the above sketch. 



A 


\ 


, 


66y 




350 


790 i 


y 


^ 


^N 


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^ 




Jx 


>* 


% 


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■^c . 


^ — ~ \ 




' 87j/> 


X o 




'""v' 


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e7i- 






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O 


O f 


^aya \ 




/\a7o 






<0 


"to iV/ 


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i 










V 




i. 










- ', 


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y 
870 \ 




4650 


/ V 




f 




V 




■^eeu 


















ees 






•B92 






'e'-5 



Arrow points on Fig. 9 (except those also appearing on Fig. 8) are 
points where contours cross streams or dry runs. 

more of it a student does the better. Anyone can make up a 
framework, similar to those shown in figures 8, 12, and 13, and 
practice contouring by logical methods. 



SKETCHING METHODS. 



39 



The procedure, as shown, is to first note the elevations of 
critical points along stream lines and ridges, then divide up and 
mark crossing points of contour lines along the* main stream 




riq.lO 



line, then along the tributary streams, marking those on stream 
lines with a V pointing upstream, then from points along the 




Fig.// 



stream lines to ridge-line points near by, mark (with dots or 
short lines) the crossing points of the number of contour lines 
that go between, according to the elevations of the top and bot- 



40 SKETCHING METHODS. 

torn points. Finally, having enough of these to shape the 
ground, join them up by long curving lines. 

On all sketches, the contour lines should be numbered so 
that the elevation of any one of them can be readily found. 
They should be numbered where they leave the area and occa- 
sionally along a stream line or on some of the longer slopes 
(fig. 11). The completed sketch should have each 50 or 100 
foot contour line drawn heavier than the others. 

CONTOUR FRAMEWORK. 

Critical points are those at which an abrupt change in direc- 
tion or slope takes place, such as bends in roads or streams, 
stream junctions, tops of ridges, hills, etc. Any feature which 
may assist the sketcher in securing his framework, may be 
called a critical point. 

Manifestly, it is impracticable to determine the exact location 
of the crossing points of each contour line between all the criti- 
cal points. It is equally impracticable to determine the location 
of every slight change of slope on a hillside. Such detail is not 
important and is not wanted. Hence, the sketcher ascertains 
the elevation of critical points, thus locating the position of 
the form-controlling contours and interpolates the contour lines 
between them, spacing by eye to indicate the change of slope as 
these changes appear to him. 

The undulations and vertical distances in the form of the 
ground are largely caused by the erosive action of rainfall, 
hence the drainage system and ridge lines form the framework 
on which contours are hung. 

If the sketcher determines: (1) The elevation of the main 
stream line at the point where it enters his area ; (2) the eleva- 
tion of its junction with its tributaries, in the area; (3) the 
elevation of the main stream where it leaves the area, he will 
have a good base from which to build up his contours. If, while 
determining the above, he also determines the elevations of the 
tops of the ridge lines between the stream branches and of im- 
portant points along and on these ridges, he will have the high- 
est as well as the lowest levels in the area and need only fill in 
the contours between the points whose elevations are known. 

The foregoing is exactly what the sketcher must do in con-, 
touring. As he goes over his area, drawing to scale the flat or 
horizontal details, he locates all critical points and estimates 
and notes their elevation. Then, having enough of the drainage 



SKETCHING METHODS. 



41 



system and ridge lines " pinned down " to enable him to show 
the big features, he dots in the level lines at their proper vertical 
intervals between critical points according to the slope of the 
ground. Finally he connects up the dotted points by contour 
lines, each running through the dots of its own elevation. 

In reality, contour lines in sketching are nothing more than 
conventional signs. A sketcher will soon find that every slope is 
one of three kinds — uniform, concave, or convex. When spac- 
ing in contours, this should be kept in mind. Any slope of 




Fig /ii. •intemola-fe 10' Contours 



ground may be divided into sections, each of which may be repre- 
sented by one of the three kinds mentioned. Practice alone will 
enable one to pick out the dividing lines, but they should be 
looked for from the beginning. 

Where the slope is uniform, space your contours equal dis- 
tances apart ; where the slope is concave in form, space your con- 
tour lines closer together near the higher elevation and wider 
apart toward the lower; where the slope is convex, space them 
wider at the higher and closer at the lower elevation. 



43 



SKETCHING METHODS. 



The beginner must learn to consider general knowledge of 
country, of rates of fall of streams, of railroad grades, and of 
ground forms in order to keep his work logical and consistent. 
For instance, large rivers have a fall of only a few inches to the 
mile, unless there are many rapids ; therefore, within the limits 
of an ordinary reconnaissance sketch, a large rivet is at the 
same level, for purposes of determining elevations. A stream 



10001 



Insa 'fise- 



ic»o6|[ 




p- I a Interpolate lO'Cor^tours. 



line carrying water all the year round has a less fall per mile 
than one in the same area which is dry part of the time. Tribu- 
tary streams have a greater fall than main stream lines. The 
nearer the stream to the source, the steeper it falls. 

NOTES FOR FIELD WORK. 



Avoid complicated and cumbersome methods. 
Alwaj-s use the simplest and most common-sense way. 
Do everything possible, consistent with requirements of 
making the sketch, to save time. When you halt to make a note. 



SKETCHING ItlETHODS. 43 

make it, and go on. When you halt to fill in something and it 
is not necessary to orient, do not orient but do the filling in 
quickly, and move on. 

Never orient the board unless there is necessity for it. 

Every time you orient the board by arrow or compass, verify 
it by a back sight, if practicable. Every time you orient by a 
jback sight, verify it by the arrow or compass. 

Always verify the orientation just before you draw a ray 
either along a traverse or in intersection or resection. 

Try to acquire the habit of doing the necessary things at 
each halt in the same sequence. For example, traversing along 
a road, you arrive at the top of a rise, to which you had drawn 
a ray. Halt there, look around, and select the best position 
for sighting forward on the traverse. Lay the board down on 
the ground or place it on your knees. Take out ruler and pencil, 
and placing ruler alongside the ray, with edge of working scale 
next to it, measure off the number of strides from last station 
and mark with pencil dot. Stick a pin in this dot which is 
your present station. Lay ruler along ray to last station and 
orient board by back sight. Having the board oriented, 
pivot the ruler around the pin and draw a ray to the next 
station. Now sight and draw rays to such points as you 
may have drawn rays to from previous station, to complete their 
location by intersection and then draw rays to such new points 
as in your judgment may be of use, noting in each case the 
object sighted. Verify orientation each time before drawing 
ray. Now draw in the other road line (the ray taken to this 
station is one) and fill in the flat details, houses, bridges, stream 
lines, fence signs, etc., from the last station to your present one. 
Determine the elevation of your present station by estimating 
the difference between it and the previous one. In the same 
manner determine the elevation of any critical points that you 
may have noted in your traverse from last station as well as 
of points located by intersection. If you have enough data to 
enable you to contour between stations, do it now ; if not, be 
sure that the elevations of critical points are noted. Put the 
ruler, pencil, eraser, pin, etc., in their proper places, pick up 
the board, and start traverse to next station. 

The operations noted in the foregoing have to be carried out 
at each station. Failure to carry them out in sequence while 
learning to sketch will handicap the beginner very much. It 



44 SKETCHING METHODS. 

is therefore considered essential tliat the beginner should learn 
to do them in the sequence described. After a while he will de- 
velop the simplest and best way for himself. 

Have your sketch completed up to your station before moving 
on. In the earlier stages this applies only to flat details, later 
to both horizontal and vertical detail in road sketching and 
to horizontal detail and the location and determination of the 
elevation of critical points in making a position sketch. The 
contouring in this case is not undertaken until the entire frame- 
work of ridge and stream lines is " pinned down." 

Be particular that the information conveyed is not misleading. 
It is better to leave a part blank than to deceive or mislead. 

Try to put equal care and time on all parts of the sketch. 
Avoid excessive care at the beginning followed by excessive haste 
near the end. 

Acquire method and system in your sketching and the rest 
will be easy. 

POSITION SKETCH. 

It is assumed that before undertaking to make a position 
sketch the sketcher has followed out the course of study outlined 
herein. 

Select an area of ground about one-half a mile square. One 
having roads on all sides is better, but this is not material. 

Determine where to locate your starting point on the paper 
by estimating the direction from you in which the area to be 
sketched lies. If you are at the southwest corner of the area, 
locate your starting point (by sticking in a pin) about 5 inches 
from the west edge and 5 inches from the south edge of the 
paper. Since the area to be sketched will occupy about 3 inches 
. square when drawn to scale, you will thus have it at about the 
center of the sheet. 

Draw the magnetic meridian line parallel to the edge of the 
paper, then orient board. Take forward sight to next station 
and draw ray toward it. Assume elevation of starting point 
and note it. Now traverse all the way around the area, locating 
as you go the position and elevation of all critical points along 
the traverse. Fill in all horizontal detail along and near the 
traverse, inside the area, within easy estimating distance (a 
couple of hundred yards) by estimation and farther off by inter- 
section methods. 



SKETCHING METHODS. 46 

In traversing around the area, in addition to cuts, fills, 
orchards, etc., locate the following : 

1. Every stream or drainage line crossing the traverse or 
running close to it. Note the direction of its flow and its fall. If 
this is not at once apparent, take time to find out. This is 
important. 

2. Every house or other feature easily identified near the 
traverse, which may later be useful in finding yourself. Some- 
times some feature outside of the area may be extremely valu- 
able. For example, a tall chimney some hundreds of yards from 
the area may be visible from all points in it ; to locate this by 
intersection early in the work may save much time later. 

3. The high points between drainage lines along the traverse 
(determine and note their elevations). Proceeding simultane- 
ously with the traversing, dot in (according to the slope of the 
ground) and mark the crossing points of the contours between 
critical points along the traverse whose elevations have been 
determined. Do not draw any contours yet; wait until later, 
when you have the stream line and ridge framework completed 
and can see the area as a whole. The big features will then be 
distinct, and the little ones will take care of themselves. 

ADJUSTMENT TO CLOSE. 

When you reach a point from which the starting point can be 
seen, you will probably find that the ray to that point does not 
pass directly through it. This is to be expected. If the error 
is less than 10 per cent of the entire length of the traverse, it is 
satisfactory. If it is greater, there has probably been some 
error in your orientation. If you are not able to determine 
just where the mistake occurred, distribute the error by ad- 
justment. To do this, move the last point to or from the point of 
starting, the next traverse line a little less in the same direc- 
tion, and the next one a little less than the previous one. Re- 
member the scale you are using and the scale width of a road 
as it is drawn on the sketch. Do not waste time in making this 
adjustment, but in making it, be sure that you do not make an 
angle between roads which is noticeably different from the 
actual ground angle made by the roads. Otherwise some one 
may be misled. Your sketch will have errors in it, but it must 
not contain misleading or deceptive information. 



46 SKETCHING METHODS. 

COMPLETING SKETCH. 

Having traversed completely around your area and having 
noted the location of all drainage lines crossing its borders, you 
will have a pretty fair idea as to which is the main stream line 
and where it lies. You must now find out how the smaller 
stream lines connect up with it in the area in order to com- 
plete your framework. It is now time to traverse into the 
Interior. Select a road or trail if one is nearby ; if not, select 
some point in the interior and draw a ray to it, being careful 
with the orientation when you draw it. Traverse along the 
road or ray and keep going until it seems advisable to stop. 
Then plot your position, fill in flat detail up to your location, 
determine your elevation, and then, after orienting the board/ 
draw rays to such stream junctions and high points as seem 
to be valuable. In this manner ti'averse across the entire area, 
locating stream lines, stream junctions, ridges, and hilltops, 
fill in flat detail, determine elevations as you go and note those 
of critical points along and near your traverse. It may be 
necessary to traverse across the area in the other direction be- 
fore all critical points are determined, but on such a small 
area it will probably not be. After having located the drainage 
framework and ridge lines and determined their elevations 
you are ready to contour. This should be done by noting the 
slopes as uniform, concave or convex, and spacing the contour 
lines accordingly. After a little practice, it should be possible 
to contour any area that the sketcher has been over, from one 
or two places from which he is able to see the slopes. Until the 
sketcher becomes pretty familiar with ground forms and their 
representation by contours, he should take time to dot in the 
crossing points of the contour lines between all adjacent critical 
points. This will take a little longer but will save much time 
later because of the practice it gives the hand and eye. 

Put on the title as described on page 26, and the sketch is 
finished. 

OUTPOST SKETCH. 

In the execution of an outpost sketch, which is made on a 
scale of 6 inches to the mile, V. I., 10 feet, the methods followed 
are the same as those of a position sketch, except that the 
sketcher is confined to one side of the area. 

Points along the outpost line are located by traversing, while 
those to the front are determinetl by intersection or, in some 



SKETCHING METHODS. 47 

cases, by estimation, as for instance, where a feature can be 
seen from one place on tlie line only. 

Having made two or three position sketches, the beginner 
should be able to start at one end of the line and carry his oper- 
ations along to the other end and then from some advantageous 
position contour the area. 

A little study of the area before starting the sketch will be 
of value in determining the best method to follow. 

Traverse the outpost line, sketching it as you go, and draw- 
ing rays from different stations to points in the foreground, 
thus locating them by intersection. 

The angle between the intersection lines should be as near 
90° as possible. Therefore, the points on a straight line from 
which the intersecting lines are drawn should be far enough 
apart, if the ground will permit, to secure this. It is thus 
evident that the farther out the points are, the farther apart 
should be the points from which the intersecting lines are drawn. 
Convei'sely, the nearer the object, the shorter need be the dis- 
tance between the points on the traverse line from which the 
rays are drawn. 

The distance to be sketched to the front depends upon the 
time available and the character of the country. In all prac- 
tice work the sketcher should include the area as far to the 
front as he can see. 

It is frequently the case in outpost sketching that it is pos- 
sible to locate and draw in one end and the direction line of a 
straight road, fence line, railroad track, or telegraph line. If 
this can be done, all points along it are accurately located by 
drawing^ a ray to them from determined points along the tra- 
verse, thereby completing the intersection. 

In contouring the outpost sketch, tlie same methods are fol- 
lowed as in the position sketch. The stream line and ridge 
framework have been secured by the sketcher in his traverse, 
and it only remains to interpolate the contours according to 
the slopes of the ground as they appear to the sketcher. 

Any part of the area that can not be seen, as the far side of a 
ridge parallel to the traverse, is drawn in by broken contour 
lines, which indicate that, in the opinion of the sketcher, the 
ground is shaped as shown by them, although he has -not 
visited it. 



48 SKETCHING METHODS. 

Field glasses may be of use in outpost sketching in picking out 
objects on which to intersect or for discovering folds in the 
ground that are not visible to the naked eye. 

PLACE SKETCH. 

A place sketch is one in which the sketcher is limited to a 
single point of observation overlooking the area to be sketched. 
The details to be shown are the same as on a position or outpost 
sketch. 

If made to extend a road or position sketch farther toward 
the enemy than can be reached by the sketcher, the place sketch 
will be at the scale of the sketch thus extended, otherwise at 
6 inches to the mile and 10-foot V. I. 

The methods of work described for making a position and 
outpost sketch are followed, except that the location of points 
is determined by estimation, assisted' by intersection methods 
where possible. 

It is advisable to select some few prominent features in the 
area, determine their position and elevation as carefully as 
possible, and then use them as reference points in locating other 
points. A road, a hedge fence, a wire fence, a railroad, or 
any such feature should be located and drawn in as soon as 
possible and used for basing other estimates and for locating 
points along it by intersection. 

Parts of the area that can not be seen, but which the sketcher 
is able to estimate, should be represented by broken lines, as in 
outpost work. 

Place sketching is extremely valuable to the beginner, who 
has progressed through position and outpost sketching, on ac- 
count of the practice that it gives in estimating distances. 

ROAD SKETCH. 

Before taking up road sketching, the beginner should be able 
to make a position sketch and should have made a few outpost 
and place sketches, for the benefit of the practice in intersection 
and estimation which he gains by them. He should also learn 
something of what can be shown to advantage on a 3-inch scale. 

It is advisable to make one or two short road sketches dis- 
mounted before taking up the road sketching proper, which is 
done mounted. 

The methods followed in road work are a combination of 
those used in the other classes of sketches which have been 



SKETCHING METHODS. 49 

described. The scale is usually 3 inches to 1 mile with V. I., 
20 feet. The sketcher lays the board on the ground or places it 
on his knees as he sits down. 

The road sketch should include all the country for 400 yards 
to each side of the road, all artillery positions within several 
miles, and all commanding positions within rifle range of about 
1 mile. It should show any prominent landmarks and where 
roads, railroads, etc., come from and go to, the names of rivers 
and larger streams, of the families living at crossroads or in 
isolated houses, of towns or villages, as well as all information 
that is given in position, outpost, or place sketches. 

Arriving at his second station, the sketcher should draw in 
not only all horizontal detail from the first station, but should 
contour the area he has passed over before starting on his next 
traverse. It is for this reason that it is considered better for 
the beginner not to attempt to make a road sketch until he is 
somewhat practiced in sketching methods. 

Do not waste time in orienting, but after laying board down 
or standing up with it leveled in front of and pressed against 
the body, orient by back sight and check by noting that arrow 
on board is to north. 

With the board held pressed against the body, to draw a 
ray to a distant object, first orient the board, then pivot the 
ruler around the pin to its approximate position, and glancing 
down at the ruler and at the object alternately, determine when 
the ruler is pointing at the object. Glance at the orientation, 
carefully secure the ruler with finger or thumb, and then draw 
.the ray. This will be found quite diflicult to do at first, but a 
little practice will make it easy. Points determined by inter- 
section of rays taken in this manner are very accurately located 
after some practice. 

The road sketch is carried along in the manner indicated from 
station to station, being completed at each point before moving 
on to the next. 

Many points within 400 yards of the road will not be visible 
to the sketcher from his position opposite them in the road, 
but they may be from some point further on. In any case, make 
it a rule not to leave the road. Fill in such places as you think 
they are, as described in outpost work, or leave them blank, 
as their character will be seen by the reader of the sketch. 



60 SKETCHIN6 HETHODS. 

In case the sketch should threaten to run off the paper, the 
procedure is to fill in the detail a little beyond your station 
(which is now close to the edge of the paper) and then, choosing 
a new point of beginning on the paper, locate your station there, 
draw a magnetic-meridian line near by, and duplicate the filling 
in previously done, around and beyond it. 

Go right ahead with this part just as though the other part 
was a different sketch, but when the sketch is finished cut the 
paper between the two parts, and laying the points which you 
filled in twice (once near the edge of the paper and again when 
you started the new part), one over the other, turn the papers 
until the M. M. lines of the two parts are parallel, and then 
paste them together in that position. The sketch may run off 
the paper several times, but so long as the finished sketch shows 
the meridian lines of all different parts parallel to each other 
this is immaterial. 

In mounted work the sketcher must, while controlling the 
horse and riding along the road, jot down the features as they 
are passed. This is done on the pad as described on page 20. 

Practice in noting down features while riding at a trot should 
be had before going out to make a sketch. It is quite difficult 
for some to learn, but anyone can do it with practice. 

System in methods of work is most important, as time is a 
big factor in mounted work. All sketching is done, as in road 
sketching, dismounted. The board is swung under the left arm 
by the cord passing over the shoulder, and the watch (if using 
the stop watch) and pad are held in the left hand, finger close 
to the stop of the watch. Using the stop watch and pad is 
largely for convenience. Satisfactory mounted work may be 
done by using an ordinary wrist watch on inner side of left wrist, 
from which the time of passing a feature, etc., may be noted on 
a pad held in left hand. 

The reins are held in the right hand, over left wrist, or 
with a knot tied in them across the pommel of the saddle, where 
they can be quickly grasped. 

If you have an assistant, which is desirable, have him carry 
the board and hold your horse when you halt. The assistant 
should be with you while rating the horse and ride either 
abreast of or behind you, as he is to do during the sketching. 

Immediately after mounting take the pad in left hand. As 
the horse starts press the stop, being careful to see that stop 
watch is at zero. 



SKETCHING ICETHODS. 61 

Keep your eyes on the country and on your watch alternately, 
so that when you see a feature you will not have to hunt for 
the proper place on the pad to locate it. It may be necessary 
at first to stand in your stirrups and lean forward with arms 
close in while making the marks in order to get readable ones. 
Note the direction of flow of the stream lines as you pass them. 

At first traverse about a minute at a time and then dismount 
and complete the sketch in the same manner as in road sketching 
dismounted. The time spent in traversing is small in compari- 
son with that spent in plotting the notes taken. 

Arriving at a halting place, stop the horse, press the watch 
stop to secure correct time or note same from watch, throw 
sketch-board cord over the head and lay the board on the 
ground, or sit down and place it on your knees. It is better to 
lie down on the ground on the stomach and with pad at hand 
and the board on the ground, measure off the minutes of travel 
and fill in flat detail and critical points according to the notes. 
Then orient the board and draw a ray to the new station or in 
the new direction along the traverse. Then, taking the board 
up as previously described, contour the sketch up to your 
position. 

In field service the information desired in a road sketch 
is largely that which will enable another to follow the recon- 
noitered road. For this reason contouring is of less importance 
than direction, distance, land marks, and condition and practi- 
cability of roads. In learning how to sketch, however, it is con- 
sidered necessary that the sketcher practice contouring in road 
sketching, not so much because he will do this in service as 
because the practice in rapid contouring is invaluable in the 
study of ground forms and their representation. 

RECONNAISSANCE SKETCHES. 

The tactical situation and the intentions of the commander 
will indicate in each case the information that is especially 
desired. The information secured is conveyed by means of a 
sketch amplified by a report in marginal notes numbered se- 
rially. All information that it is possible to show clearly is 
contained in the sketch. The report consists of descriptions of 
features and objects, measurements, material, construction, etc., 
which can not be conveyed in a sketch. The serial reference 
numbers should run in order on the margin. The numbers are 



62 SKETCHING METHODS. 

placed on the sketch near the object to which they pertain, so 
that it will be clear to what they refer. In making the notes 
clearness and brevity are desirable. Such terms as " before," 
" behind," " this side of," etc., should be avoided and compass 
directions used. The terms " left " and " right " may be used in 
referring to the banks of a stream, in which case the sketcher 
is assumed to be facing downstream. 

o 



